This nonprovisional application claims priority under 35 U.S.C. xc2xa7119(a) on Patent Application No. 2001-334727 filed in JAPAN on Oct. 31, 2001, which is herein incorporated by reference.
The present invention relates to a multi-piece solid golf ball. More particularly, it relates to a multi-piece solid golf ball, which is superior in flight distance, spin performance, shot feel and scuff resistance.
As golf balls with high spin performance at approach shot and long flight distance, two-layer structured core type or two-layer structured cover type golf balls have been proposed which comprise a center formed from soft rubber, an intermediate layer formed on the center and from rubber or resin that is relatively harder than the center and a cover formed from soft material (Japanese Patent No. 2910516, Japanese Patent Publication Nos. 151226/1998, 151320/1999 and the like).
In Japanese Patent No. 2910516, a multi-piece golf ball, of which the center has a diameter of not less than 29 mm, the intermediate layer has a JIS-C hardness of not less than 85, and the specific gravity of the center is larger than that of the intermediate layer, is described. However, since the thickness of the cover is large, which is within the range of 1 to 3 mm, the rebound characteristics of the resulting golf ball are poor, and the flight distance when hit by a driver is not sufficiently obtained.
In Japanese Patent Publication No. 151226/1998, a multi-piece golf ball, of which the center has a distortion of at least 2.5 mm under a load of 100 kg, the Shore D hardness of the intermediate layer is at least 13 degrees higher than that of the cover, and the ball as a whole has an inertia moment of at least 83 g-cm2, is described. However, since the cover is soft and the thickness of the cover is large, which is within the range of 1 to 3 mm, the rebound characteristics of the resulting golf ball are poor and the hit golf ball creates blown-up trajectory, and the flight distance when hit by a driver is not sufficiently obtained.
In Japanese Patent Publication No. 151320/1999, a multi-piece golf ball, of which the center and intermediate layer are formed from rubber composition comprising polybutadiene rubber as a main component, the center has a diameter of 15 to 22 mm and a Shore D hardness of 40 to 70, is described. However, the diameter of the center is too small, and the rebound characteristics of the resulting golf ball are poor. In addition, the spin amount at the time of hitting is large, and the flight distance when hit by a driver is not sufficiently obtained.
There has been no golf ball, which is superior in flight distance, shot feel, controllability (spin performance) and scuff resistance.
A main object of the present invention is to provide a multi-piece solid golf ball, which is superior in flight distance, controllability, shot feel and scuff resistance.
According to the present invention, the object described above has been accomplished by providing a multi-piece solid golf ball comprising a center, intermediate layer and cover, using polyurethane-based thermoplastic elastomer for the cover, and by adjusting the diameter of the center, the thickness and hardness of the intermediate layer, the hardness difference and specific gravity difference between the intermediate layer and the center, the thickness of the cover, the hardness difference and specific gravity difference between the intermediate layer and the cover to specified ranges, thereby providing a multi-piece solid golf ball, which is superior in flight distance, controllability, shot feel and scuff resistance.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.